Locking bar arrangement for securing electronic assemblies

ABSTRACT

A locking bar arrangement is disclosed for securing a plurality of electronic assemblies disposed in a mounting frame and arranged in a row one next to the other. The edges of the electronic assemblies are locked by means of elastic formed members in a vibration-proof manner. Separate fastening of each assembly is therefore not necessary and it is sufficient to fasten only a locking bar to a mounting frame. The locking bar can be attached to the mounting frame so that it can be tilted to permit removal of the assemblies from the mounting frame without having to take the locking bar out completely. Designation markings can be applied on the locking bar and their correspondence to appropriate assemblies is maintained.

United States Patent [191 [111 3,831,064 Keller Aug. 20, 1974 LOCKING BAR ARRANGEMENT FOR SECURING ELECTRONIC ASSEMBLIES Inventor: Roman Keller, Erlangen, Germany Siemens Aktiengesellschaft, Munchen, Germany Filed: Mar. 22, 1973 Appl. No.: 343,956

Assignee:

Foreign Application Priority Data Mar. 24, 1972' Germany 2214537 References Cited UNITED STATES PATENTS 7/1963 Bleier 3l7/l0l DH 12/1967 Haury 317/101 DH 2/1971 l-luebner 3l7/l0l DH Primary Examiner-Robert K. Schaefer Assistant Examiner- Gerald P. Tolin Attorney, Agent, or Firm-Kenyon & Kenyon Reilly Carr & Chapin [5 7] ABSTRACT A locking bar arrangement is disclosed for securing a plurality of electronic assemblies disposed in a mounting frame and arranged in a row one next to the other. The edges of the electronic assemblies are locked by means of elastic formed members in a vibration-proof manner. Separate fastening of each assembly is therefore not necessary and it is sufficient to fasten only a locking bar to a mounting frame. The locking bar can be attached to the mounting frame so that it can be tilted to permit removal of the assemblies from the mounting frame without having to take the locking bar out completely. Designation markings can be applied on the locking bar and their correspondence to appropriate assemblies is maintained.

16 Claims, 4 Drawing Figures LOCKING BAR ARRANGEMENT FOR SECURING ELECTRONIC ASSEMBLIES BACKGROUND OF THE INVENTION The invention relates to a locking bar arrangement for securing electronic assemblies which are lined up side-by-side in a mounting frame. The locking bar of the arrangement covers one edge of each of the assemblies.

Mounting frames wherein electronic assemblies can be lined up side-by-side as so-called plug-in assemblies are common in the industry. The attachment of the individual assemblies by means of the connectors is in general not sufficient and additional fasteners must be provided. In the commercially available mounting frames each assembly is individually bolted to the mounting frame for this purpose. This is necessary particularly if the mounting frame with the assemblies is to be subjected to vibration and shock loads. However, it is found that under increased shock loading the screwfastened assemblies still are not secured in a vibrationproof manner, so that destruction of electrical connections or possibly of entire assemblies can occur. Assemblies which are mounted in commercially available mounting frames are therefore not supported in an operationally reliable manner.

A further difficulty arises if assemblies must be removed from the mounting frame, for instance, for repair purposes. Because markings can be applied only with difficulty to commercially available mounting frames, increased care is necessary in correlating the removed assemblies with their mounting locations. In a known locking bar such as disclosed, for instance, in Deutsche Gebrauchsrnuster 1,894,755, the correlation is preserved by the provision that the locking bar is attached at the mounting frame so that it can be tilted about an axis which is parallel to the axis of the bar. For removing assemblies this locking bar merely has to be hinged up or down to make the assemblies accessible. Markings which are applied to this bar are always readable and mark the mounting location of the assemblies unambiguously. However, the fastening of the individual assemblies in the mounting frame cannot be dispensed with in this locking bar. The known locking bar is furthermore held in its stable end positions only by spring force and this can lead to an unintentional displacement of the bar.

SUMMARY OF THE INVENTION It is an object of the invention to provide a locking bar arrangement for securing electronic assemblies in a mounting frame in a vibration-proof manner with little manual effort.

The locking bar arrangement of the invention secures a plurality of electronic assemblies disposed in a mounting frame and arranged in a row one next to the other. The locking bar arrangement includes as a feature a locking bar mountable on the frame for securing the assemblies therein. The locking bar has a surface directed toward the assemblies for covering over an edge of each of the assemblies when mounted for securing the same. Fastening means are provided for removably bolting the locking bar to the mounting frame. An elastic formed member is disposed at this surface of the locking bat and extends therealong for substantially the entire length of the locking bar. The formed memher is arranged in elevation on this surface with respect to the respective edges of the assemblies covered by the locking bar so as to cause the formed member to have pressed portions conjointly surrounding the edges of the assemblies when the locking bar is bolted to the mounting frame.

Each of the electronic assemblies has two mutually adjacent sides defining an edge angle and conjointly forming the edge of the assembly covered over by the locking bar. The formed member has a contour and a location on the surface of the locking bar facing the assemblies which are selected so as to cause the pressed portions thereof to apply a force to the edge of each assembly in a direction coincident with the bisector of the edge angle.

By pressing the assemblies in by means of the elastic formed member, relative motion between the assemblies and the carrier is prevented. With the locking bar according to the invention, a fastening of the assemblies in the mounting frame is therefore achieved in a simple manner, which withstands practically any normal shock and ensures that the assemblies will operate reliably. In special cases, for instance, for high vibration and shock loads, two identical locking bars can be provided at the upper and lower edges of the assemblies. Assemblies which are held in the mounting frame in this manner can be used in rail vehicles for example or under other, similar conditions without the danger of an operational failure because the assemblies are not adequately secured.

The elastic formed member can be a rope-like material which is pushed into a mounting of the locking bar and it may be of circular cross-section.

It is advantageous to provide the locking bar with at least one projection, a portion of which fits tightly into a part of a recess in the mounting frame. This projection serves for centering the locking bar in the mounting frame and, at the same time, it relieves the fastening screws because it serves as a support element when the assemblies are pressed into the elastic formed member. This projection can be a longitudinal stiffening rib of the locking bar.

In a particularly advantageous further embodiment of the locking bar according to the invention, screws are provided for fastening on the mounting frame. The threaded part of the screws is interrupted by a section of smaller diameter. For each screw a bore is provided at the mounting frame which is enlarged after the screw thread to form a cavity. A locking bar secured in this manner can be pulled out horizontally after the fastening screws have been loosened, and can easily be tilted up or down. This clears a way for the insertable assemblies without the necessity of first removing the locking bar completely. Thus, the aforementioned fastening means can include screws mounted on the locking bar and respective bore means formed in the mounting frame for accommodating the screws therein. Each of the bore means has an innermost portion and an ancillary portion adjacent the innermost portion. Winding means are at the ancillary portion for threadably engaging a corresponding one of the screws when the locking bar is bolted to the mounting frame and for facilitating the movement of the shank portion through the winding means when the screw is threadably disengaged from the same whereby the locking bar can be moved a distance away from the mounting frame and tilted about an axis parallel to the longitudinal axis of the locking bar. The innermost portion is disposed in the mounting frame beyond the ancillary portion and is expanded to form a cavity. The ancillary portion of each of the bore means can include at least one groove formed in the mounting frame and the winding means can be a nut threadably engaging the screw corresponding to the bore means. The groove has a width greater than the thickness of the nut.

With this embodiment which permits tilting of the locking bar, markings can be arranged on the front of the locking bar which will therefore always remain readable and uniquely related to the mounting locations of the assemblies. The locking bar attached in this manner can be hinged only after the fastening screws are loosened. Unintended tilting during operation, which can occur with the known locking bar, is therefore prevented. It should be emphasized that securing assemblies with a locking bar which is hinge mounted is not limited only to a locking bar in which the assemblies are locked so as to be vibration-proof with the aid of an elastic formed member. The particular advantages of this type of securing arrangement remain if it is used in connection with a locking bar which does not afford an absolutely vibration-proof fastening of the assemblies.

The locking strip according to the invention makes possible the vibration-proof locking of assemblies in assembly carriers also for rugged operation. Moreover, the repair and exchange of assemblies are facilitated because the mounting location in the mounting frame remains unambiguously marked. It should further be pointed out that the locking bar can be made as a profiled rod by an extrusion process and no particular effort is required for mass production of the same. The longitudinal slot to receive the stiffening rail and the fastening screws can also be produced as an extrusion and fastened separately in the mounting frame.

Although the invention is illustrated and described herein as a locking bar arrangement for securing electronic assemblies, it is nevertheless not intended to be limited to the details shown, since various modifications may be made therein within the scope and the range of the claims. The invention, however, together with additional objects and advantages will be best understood from the following description and in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the locking arrangement for securing electronic assemblies according to the invention are illustrated in the FIGS. described below. Similar or like components are designated by the same reference numeral in each FIG. in which they appear.

FIG. 1 is a schematic diagram of an elevation front view of a mounting frame equipped with two locking bar arrangements according to the invention. One of the locking bars is shown at the top edge of the electronic assemblies mounted in the frame and the other locking bar is at the lower edge of the assemblies.

FIG. 2 is a section view taken along the line IIII of FIG. I at the region of the lower locking bar.

FIG. 3 is a section view taken along line III-III of FIG. 1 and shows a screw connection.

FIG. 3a is a section view also taken along line III-III showing the locking bar in the extended released position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Referring to FIG. 1, a mounting frame 1 is shown in which the front panels 2a to 2g of several electronic assemblies are lined up side-by-side. The lower edges 3 and the upper edges 4 of each front panel 2 are covered by respective bars 6a and 6b which are each fastened in the mounting frame 1 by fastening means which can comprise two screws. Bar 6a is fastened by screws 7a and 7b and bar 6b by screws 8a and 812. With this locking system in which two locking bars 6a and 6b are utilized, the assemblies 2 in the assembly carrier 1 are locked in a vibration-proof manner which ensures operational reliability even when subjected to increased vibration and shock.

In FIG. 2, a cross-section is shown of the locking bar arrangement of the invention at the lower edge of the assemblies and includes locking bar 6a. The locking bar 60 is provided with -a projection 9 which in the illustrated embodiment is a longitudinal stiffening rib. A portion 9a of the longitudinal stiffening rib 9 fits essentially in a form-tight manner in a partial region 10a of a longitudinal slot 10.

The further special configuration of the longitudinal slot 10 will be discussed in greater detail below. The locking bar 6a is centered in the mounting frame by means of the portion 9a of the longitudinal rib 9. This portion 9a further takes up the counterforces generated when the locking bar is screw fastened and relieves load on the screws 7.

An elastic, rope-like formed member 12 of circular cross-section is pushed into holding means in the form of a groove 11 of the locking bar 6a. The cross-section of the groove 11 corresponds to the sector of a circle. The elastic insert 12 can be made of a foam material for example. The rope-like material may also have a rectangular or triangular cross-section. The mounting groove 11 for the rope-like molding 12 is arranged in the locking bar 6a at the height of the front panel 2 of the electronic assembly. For the bolted condition, shown in FIG. 2, the lower edge 3 of the front panel 2 is pressed into the elastic rope l2 and is surrounded by the compressed parts of this rope. This results in a force which is essentially in the direction of the bisector of the angle defined by the edge 3. The direction of this force which corresponds to the bisector of the angle is indicated in FIG. 2 by the arrow 13.

The force exerted by the elastic molding 12 on the front panel causes the assembly to be held to a large extent in a vibration-proof manner in the assembly carrier 1 and relative displacement between the assemblies cannot occur. If special loadings are expected, a second locking bar can be provided which likewise acts on the front panel 2 via an elastic molding as described above. A mounting frame according to FIG. 1, in which the electronic assemblies are secured in this manner, can also be subjected to extreme conditions such as on a rail vehicle without the danger of operational failures because of vibrations.

The locking bar 6a has two surfaces 14 and 15 on which markings can be applied. On the marking surface 15, designation strips can be inserted into grooves 15a and 15b. The markings on these designation strips correspond to the different individual assemblies. In FIG. 1 the markings for the individual assemblies 2 are indicated by the lettering panels 21a to 213.

The cross-section of FIG. 3 is taken along the line III- -III of FIG. 1 and shows the particular kind of screw attachment which is selected for the illustrated embodiment and which can also be used, as already emphasized, for other locking bars. The locking bar 6a is bolted into the mounting frame 1 by means of screws 7 which have a threaded part 7a and 7b between which a portion 7c of the screw is provided which has a smaller diameter than the threaded part. The longitudinal slot 10 can be considered as having an innermost portion 19 and an ancillary portion 30 adjacent the innermost portion. The threaded part 7a of the screw 7 threadably engages winding means in the form of a nut 17 which is inserted into grooves 18 at the ancillary portion 30 of the longitudinal slot 10. The width of the grooves 18 is here substantially larger than the thickness of the nut 17. The section 7c of the screw 7 and the second threaded part 7b protrude into the cavity 19 of the longitudinal slot 10, the height of which is greater than the threaded bore of the nut 17. In lieu of the longitudinal slot 10, a corresponding bore can be arranged in the mounting frame 1, if the longitudinal stiffening rib 9 for the locking bar 6a is omitted.

If the screw 7 is threadably disengaged from the nut 17, the screw 7 and with it, the locking bar 6a can be removed from the mounting frame for the entire length of the section 70 of the screw. This condition is shown in cross-section of FIG. 3a. Because the diameter of the section 7c is smaller than the diameter of the threaded parts 7a and 7b and because the nut 17 can be tilted in the groove 18, the locking bar 6a which has already been pulled away from the mounting frame, can be tilted in the vertical direction downward or upward about an axis which is parallel to the longitudinal axis of the locking bar. The possible tilting angle mustin this connection be made large enough so that the assemblies can be withdrawn from the mounting frame or inserted into it without the edge 3 of the front panel 2 touching the locking bar. In FIG. 3a this extreme position of the locking bar 6a is depicted by the broken line 20 which describes the path of the lower edge of the front panel 2 when the assembly is withdrawn or inserted. This manner of tilting of the locking bar is advantageous because the marking on the locking bar remains unambiguously related to the mounting location of the assemblies and the markings are always readable.

What is claimed is:

l. A locking bar arrangement for securing a plurality of electronic assemblies disposed in a mounting frame and arranged in a row one next to the other comprising a locking bar mounted on the frame securing the assemblies therein, said locking bar having a surface directed toward the assemblies covering over an edge of each of the assemblies for securing the same, fastening means for removably bolting said locking bar to the mounting frame, and an elastic formed member disposed at said surface of said locking bar and extending therealong for substantially the entire length of said locking bar, said formed member being arranged on said surface with respect to the respective edges of the assemblies covered by said locking bar so as to cause said formed member to have pressed portions conjointly surrounding said edges when said locking bar is bolted to the mounting frame.

2. The locking bar arrangement of claim 1, each of the electronic assemblies having two mutually adjacent sides defining an edge angle and conjointly forming the edge of the assembly covered over by said locking bar, said formed member having a contour and a location on said surface causing said pressed portion thereof to apply a force to the edge of each assembly in a direction coincident with the bisector of the edge angle.

3. The locking bar arrangement of claim 2, said elastic formed member being made of a foam material.

4. The locking bar arrangement of claim 2, said elastic formed member being made of rope-like material, holding means formed in said surface of said locking bar for receiving said formed member inserted therein.

5. The locking bar arrangement of claim 4, said elastic formed member having a circular cross-section.

6. The locking bar arrangement of claim 5, said holding means being a groove extending longitudinally along said locking bar, said groove having a crosssectional contour corresponding to the sector of a circle.

7. The locking bar arrangement of claim 1, said locking bar having at least one projection, and cavity means formed in the mounting frame for receiving said projection therein, said cavity means and said projection having respective portions configured so as to be mutually engaged in a form-fit manner.

8. The locking bar arrangement of claim 7, said projection extending longitudinally along said bar so as to constitute a stiffening rib therefor.

9. The locking bar arrangement of claim 7, said locking bar having a longitudinal axis, said fastening means comprising screws mounted on said locking bar and extending into said cavity means, each of said screws having a thread interrupted by an intermediate shank portion, said screw having a diameter at said intermediate shank which is less than the diameter at said thread, said cavity means having an innermost portion and an ancillary portion adjacent said innermost portion, said innermost portion and said ancillary portion both being disposed beyond said first-mentioned portion of said cavity means engaging said portion of said projection of said locking bar, and winding means at said ancillary portion for threadably engaging a corresponding one of said screws when said locking bar is bolted to the mounting frame and for facilitating the movement of said shank portion through said winding means when said screw is threadably disengaged from the same whereby said locking bar can be moved a distance away from the mounting frame and tilted about an axis parallel to said longitudinal axis, said innermost portion being disposed in the mounting frame beyond said an cillary portion and being expanded to form a cavity.

10. The locking arrangement of claim 9, said ancillary portion of said cavity means including at least one groove formed in the mounting frame, and said winding means being a nut threadably engaging said corresponding screw, said groove having a width greater than the thickness of said nut.

11. The locking bar arrangement of claim 1, said locking bar having a longitudinal axis, said fastening means comprising screws mounted on said locking bar, each of said screws having a thread interrupted by an intermediate shank portion, said screw having a diameter at said intermediate shank portion which is less than the diameter at said thread, respective bore means formed in the mounting frame for accommodating said screws therein, each of said bore means having an innermost portion and an ancillary portion adjacent said innermost portion, and winding means at said ancillary portion for threadably engaging a corresponding one of said screws when said locking bar is bolted to the mounting frame and for facilitating the movement of said shank portion through said winding means when said screw is threadably disengaged from the same whereby said locking bar can be moved a distance away from the mounting frame and tilted about an axis parallel to said longitudinal axis, said innermost portion being disposed in the mounting frame beyond said ancillary portion and being expanded to form a cavity.

12. The locking arrangement of claim 11, said ancillary portion of each of said bore means including at least one groove formed in the mounting frame, and said winding means being a nut threadably engaging the screw corresponding to said bore means, said groove having a width greater than the thickness of said nut.

13. A locking bar arrangement for securing a plurality of electronic assemblies disposed in a mounting frame and arranged in a row, one next to the other, comprising a locking bar mounted on the frame and securing the assemblies therein, said locking bar having a surface directed toward the assemblies covering an edge of each of the assemblies for securing the same, said locking bar having a longitudinal axis, and fastening means comprising screws mounted on said locking bar, each of said screws having a thread interrupted by an intermediate shank portion, said screw having a diameter at said intermediate shank portion which is less than the diameter at said thread, respective bore means formed in the mounting frame accomodating said screws therein, each of said bore means having an innermost portion and an ancillary portion adjacent said innermost portion, said ancillary portion being of a smaller diameter at least at the boundary between said innermost portion and said ancillary portion and winding means at said ancillary portion threadably engaging a corresponding one of said screws when said locking bar is bolted to the mounting frame and for facilitating the movement of said shank portion through said winding means when said screw is threadably disengaged from the same whereby said locking bar can be moved a distance away from the mounting frame and tilted about an axis parallel to said longitudinal axis, said innermost portion being disposed in the mounting frame beyond said ancillary portion and being expanded to form a cavity.

14. The locking arrangement of claim 13, said ancillary portion of said bore means including at least one groove formed in the mounting frame, and said winding means being a nut threadably engaging said corresponding screw, said groove having a width greater than the thickness of said nut.

15. The locking bar arrangement of claim 13, said locking bar having at least one projection, and cavity means formed in the mounting frame for receiving said projection therein, said cavity means and said projection having respective portions configured so as to be mutually engaged in a form-fit manner when said locking bar is bolted to the mounting frame and wherein said cavity forms said respective bore means with said innermost portion and said ancillary portion both being disposed beyond said first-mentioned portion of said cavity means engaging said portion of said projection of said locking bar.

16. The locking arrangement of claim 15, said ancillary portion of said cavity means including at least one groove formed in the mounting frame, and said winding means being a nut threadably engaging said corresponding screw, said groove having a width greater than the thickness of said nut.

7 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Petent No. 3,831,064 Dated August 20. 197A Inventofls) Roman Keller I It: is certified that error appears in the above-identified patent and'that said Letters Patent are hereby corrected as shown below:

' n Columnl, line 67, change ...l'ocki ng bat..."

I I T to -ru lockingbarefl I I Q In Column 6 line 36 (claim 9"), change .intermediate 'sharik which, to ..int e rmediate shahk I -poroion which.

9 Signed an d sealed this 24th day of December1974.

k (SEAL) f Attest: H I i McCOY M. GIBSON" JR.- 7 lo. MARSHALL DANN Attest-ing Officer Commissioner of Patents FSRM po'wso 0459) I Q I USCOMM-DC 60576-P69 W U.S. GOVIRIIIINT PIIIII'IIIG OFFICE Ill 0-106-831.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,831,06A Dated August 20'. 197A Inventor(s) Roman Keller ppears in the above-identified patent It is certified that error a hereby corrected as shown below:

and that said Letters Patentare In Column 1, line 67,- change .locking bat.

I to ..locking barHQ I In Column 6, line 36 (claim 9"), change 0 --...int e rmediate shank ...intermediate Signed andsealed this 24th day of December 1974.

(SEAL) Attest: McCOY M. GIBSON JR. 7 1c. MARSHALL DANN Attesting Officer Commissioner of Patents UsCOMM-DC 60376-969 u.s. GOVERNMENT PRINTING ornc: l96 os66-sa4.

F ORM PO-105O (10459) 

1. A locking bar arrangement for securing a plurality of electronic assemblies disposed in a mounting frame and arranged in a row one next to the other comprising a locking bar mounted on the frame securing the assemblies therein, said locking bar having a surface directed toward the assemblies covering over an edge of each of the assemblies for securing the same, fastening means for removably bolting said locking bar to the mounting frame, and an elastic formed member disposed at said surface of said locking bar and extending therealong for substantially the entire length of said locking bar, said formed member being arranged on said surface with respect to the respective edges of the assemblies covered by said locking bar so as to cause said formed member to have pressed portions conjointly surrounding said edges when said locking bar is bolted to the mounting frame.
 2. The locking bar arrangement of claim 1, each of the electronic assemblies having two mutually adjacent sides defining an edge angle and conjointly forming the edge of the assembly covered over by said locking bar, said formed member having a contour and a location on said surface causing said pressed portion thereof to apply a force to the edge of each assembly in a direction coincident with the bisector of the edge angle.
 3. The locking bar arrangement of claim 2, said elastic formed member being made of a foam material.
 4. The locking bar arrangement of claim 2, said elastic formed member being made of rope-like material, holding means formed in said surface of said locking bar for receiving said formed member inserted therein.
 5. The locking bar arrangement of claim 4, said elastic formed member having a circular cross-section.
 6. The locking bar arrangement of claim 5, said holding means being a groove extending longitudinally along said locking bar, said groove having a cross-sectional contour corresponding to the sector of a circle.
 7. The locking bar arrangement of claim 1, said locking bar having at least one projection, and cavity means formed in the mounting frame for receiving said projection therein, said cavity means and said projection having respective portions configured so as to be mutually engaged in a form-fit manner.
 8. The locking bar arrangement of claim 7, said projection extending longitudinally along said bar so as to constitute a stiffening rib therefor.
 9. The locking bar arrangement of claim 7, said locking bar having a longitudinal axis, said fastening means comprising screws mounted on said locking bar and extending into said cavity means, each of said screws having a thread interrupted by an intermediate shank portion, said screw having a diameter at said intermediate shank which is less than the diameter at said thread, said cavity means having an innermost portion and an ancillary portion adjacent said innermost portion, said innermost portion and said ancillary portion both being disposed beyond said first-mentioned portion of said cavity means engaging said portion of said projection of said locking bar, and winding means at said ancillary portion for threadably engaging a corresponding one of said screws when said locking bar is bolted to the mounting frame and for facilitating the movement of said shank portion through said winding means when said screw is threadably disengaged from the same whereby said locking bar can be moved a distance away from the mounting frame and tilted about an axis parallel to said longitudinal axis, said innermost portion being disposed in the mounting frame beyond said ancillary portion and being expanded to form a cavity.
 10. The locking arrangement of claim 9, said ancillary portion of said cavity means including at least one groove formed in the mounting frame, and said winding means being a nut threadably engaging said corresponding screw, said groove having a width greater than the thickness of said nut.
 11. The locking bar arrangement of claim 1, said locking bar having a longitudinal axis, said fastening means comprising screws mounted on said locking bar, each of said screws having a thread interrupted by an intermediate shank portion, said screw having a diameter at said intermediate shank portion which is less than the diameter at said thread, respective bore means formed in the mounting frame for accommodating said screws therein, each of said bore means having an innermost portion and an ancillary portion adjacent said innermost portion, and winding means at said ancillary portion for threadably engaging a corresponding one of said screws when said locking bar is bolted to the mounting frame and for facilitating the movement of said shank portion through said winding means when said screw is threadably disengaged from the same whereby said locking bar can be moved a distance away from the mounting frame and tilted about an axis parallel to said longitudinal axis, said innermost portion being disposed in the mounting frame beyond said ancillary portion and being expanded to form a cavity.
 12. The locking arrangement of claim 11, said ancillary portion of each of said bore means including at least one groove formed in the mounting frame, and said winding means being a nut threadably engaging the screw corresponding to said bore means, said groove having a width greater than the thickness of said nut.
 13. A locking bar arrangement for securing a plurality of electronic assemblies disposed in a mounting frame and arranged in a row, one next to the other, comprising a locking bar mounted on the frame and securing the assemblies therein, said locking bar having a surface directed toward the assemblies covering an edge of each of the assemblies for securing the same, said locking bar having a longitudinal axis, and fastening means comprising screws mounted on said locking bar, each of said screws having a thread interrupted by an intermediate shank portion, said screw having a diameter at said intermediate shank portion which is less than the diameter at said thread, respective bore means formed in the mounting frame accomodating said screws therein, each of said bore means having an innermost portion and an ancillary portion adjacent said innermost portion, said ancillary portion being of a smaller diameter at least at the boundary between said innermost portion and said ancillary portion and winding means at said ancillary portion threadably engaging a corresponding one of said screws when said locking bar is bolted to the mounting frame and for facilitating the movement of said shank portion throUgh said winding means when said screw is threadably disengaged from the same whereby said locking bar can be moved a distance away from the mounting frame and tilted about an axis parallel to said longitudinal axis, said innermost portion being disposed in the mounting frame beyond said ancillary portion and being expanded to form a cavity.
 14. The locking arrangement of claim 13, said ancillary portion of said bore means including at least one groove formed in the mounting frame, and said winding means being a nut threadably engaging said corresponding screw, said groove having a width greater than the thickness of said nut.
 15. The locking bar arrangement of claim 13, said locking bar having at least one projection, and cavity means formed in the mounting frame for receiving said projection therein, said cavity means and said projection having respective portions configured so as to be mutually engaged in a form-fit manner when said locking bar is bolted to the mounting frame and wherein said cavity forms said respective bore means with said innermost portion and said ancillary portion both being disposed beyond said first-mentioned portion of said cavity means engaging said portion of said projection of said locking bar.
 16. The locking arrangement of claim 15, said ancillary portion of said cavity means including at least one groove formed in the mounting frame, and said winding means being a nut threadably engaging said corresponding screw, said groove having a width greater than the thickness of said nut. 